Sodium- and bicarbonate-independent regulation of intracellular pH in culture mouse astrocytes.
The intracellular pH (pHi) of cultured mouse astrocytes was measured with double-barrelled pH-sensitive microelectrodes. In bicarbonate-buffered saline pHi was 7.05 and in HEPES-buffered saline 6.68. In both solutions H+ was not in electrochemical equilibrium; pHi was 0.7-1 pH unit more alkaline than expected from passive H+ distribution. Cells were acidified by applying NH4+ and the subsequent regulation of pHi was studied in bicarbonate-free saline. The mean rate of pHi recovery was 0.2 pH units min-1 which was not changed by amiloride or by removal of external Na+. Thus, the cells recovered from an acid load independently of Na(+)-H+ exchange, Na(+)-HCO3- cotransport or any other bicarbonate- or Na(+)-dependent mechanism.
Wuttke
W A
WA
Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada.
Walz
W
W
D000584:Amiloride / Q000494:pharmacology; D000641:Ammonia / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D001639:Bicarbonates / Q000494:pharmacology*; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D012964:Sodium / Q000494:pharmacology*
D001639:Bicarbonates; D000641:Ammonia; D000584:Amiloride; D012964:Sodium